Multi-headed piston downhole drill



May 5, 1964 E. s. OELKE MULTI-HEADED PISTON DOWNHOLE DRILL 3 Sheets-Sheet 1 Filed Nov. 1, 1962 INVENTOR ERW/N S. OEL/(E BY QM WT ATTORNEY May 5, 1964 E. s. OELKE MULTI-HEADED PISTON DOWNHOLE DRILL .5 Sheets-Sheet 2 Filed NOV. 1, 1962 W LOT" ATTORNEY FIG. 9

y 5, 1964 E. s. OELKE 3,131,606

MULTI-HEADED PISTON DOWNHOLE DRILL Filed Nov. 1, 1962 5 Sheets-Sheet 5 INVENTOR ERW/IV .S. GEL/(E BY QM MTM ATTORNEY United States Patent 3,131,606 MULTI-HEADED PESTON DOWNHOLE DRILL Erwin S. Oelke, Easton, Pa, assignor to Ingersoll-Rand Company, New York, N.Y., a corporation of New Eersey Filed Nov. 1, 1962, Ser. No. 234,614 6 Claims. (61. 91-315) A downhole drill is a drill used for drilling holes in the earth and having a percussive mechanism which travels down the hole with the hole drilling bit. This invention relates to a pneumatically operated downhole drill which is particularly adapted for drilling holes in rock and contains a reciprocating piston having multiple heads or actuating faces.

In a downhole drill of this type, the multiple heads or actuating faces of the piston are arranged in axially spaced relationship, to provide a large actuating surface area within a relatively small diameter, and these piston heads are contained within a series of axially aligned and longitudinally spaced piston actuating chambers adapted to receive pressure fluid for reciprocating the piston back and forth within the drill body. Generally, these chambers are fed fluid pressure from the rear or upper end of the drill along passages formed in the side walls of the drill body and they are exhausted to the front or lower end of the drill along other passages likewise provided in the side walls of the drill body. Heretofore, these fluid inlet and exhaust passages in the side walls of the drill body have not been large enough, and, as a result, have provided an undesirable pressure drop and restriction to the flow of both the inlet and exhaust fluid into and out of the various piston actuating chambers.

The principal objects of this invention are to substantially eliminate or minimize the foregoing problem and to provide a greatly improved multiple piston downhole rock drill.

Another important object of this invention is to provide a novel system of inlet and exhaust passages in the side walls of a downhole drill which provides a greatly improved flow of inlet and exhaust fluid pressure.

In brief, the above objects are attained by tapering or stepping the side wall passages so that the cross-sectional areas of the inlet passages are progressively reduced as they extend forwardly in the drill body and the cross-section of the exhaust passage is progressively increased as it runs forwardly in the drill. Tapering the passages allows them to be of large cross-sectional area at the point where the volume of fluid flow is the maximum and to be of small cross-sectional area where the minimum volume of fluid flow occurs. This arrangement allows the side walls of the drill to contain a much more effective and efficient series of inlet and exhaust passages than if the passages were of uniform cross-sectional area from end-to-end.

The invention is described in connection with the accompanying drawings wherein:

FIG. 1 is a longitudinal section of a drill incorporating one embodiment of my invention;

FIGS. 2 to 6 are sections taken on corresponding lines in FIG. 1;

FIGS. 7 and 8 are perspective views of the cylinder of FIG. 1;

FIG. 9 is a representation of the total exterior surface of the cylinder in a flat or non-cylindrical condition;

FIGS. 10 and 11 are perspective views of another embodiment of cylinder; and

FIG. 12 is a view similar to FIG. 9 of the cylinder embodiment shown in FIGS. 10 and 11.

In general, the downhole drill 1 shown in the drawings comprises an elongated outer cylindrical body or casing ice 2 carrying a slidably mounted bit 3 at its lower end and containing a percussive mechanism for delivering periodic impacts to the bit 3 during the drilling of a hole in the earth. The drill further includes a backhead 4 which is threaded into the upper end of the outer casing 2 and contains an axial bore 5. The backhead 4 has threads 6 at its upper end adapted to be attached to the lower end of a drill string of pipes (not shown) which supports the drill 1 in its hole and conveys pneumatic pressure fluid to the axial bore 5 for operating the percussive mechanism of the drill 1. All of the foregoing structure is conventional in most downhole rock drills.

The percussive mechanism includes an elongated inner cylinder 9 snugly nested within the outer casing 2 and a plural-headed piston 10 reciprocating in the cylinder 9. Although the drawing shows the cylinder 9 as one integral piece, it normally is made of several axially aligned pieces to facilitate the assembly of the piston 10 in the cylinder. The piston is shown as having four enlarged heads designated 11 to 14 and joined by integral stems 15 which extend through annular partitions 16 formed on the interior of the cylinder 9. The piston heads 11 to 14 and partitions 16 cooperate to form a pair of fluid actuating chambers for each piston head 11 to 14, one chamber being termed a piston advancement chamber 17 and the other a piston retraction chamber 18. It will be understood that each piston head is located between a piston advancement chamber 17 on its upper face and a piston retraction chamber 18 on its lower face.

The piston retraction chamber 18 for the lower piston head 14 is formed between the piston head 14 and an enlarged cylindrical anvil Z6 integrally formed on the upper end of the bit 3.

As is well known in the art, pneumatic fluid pressure is alternately delivered to the advancement and retraction chambers 17 and 18 to reciprocate the piston 10. Fluid pressure is fed to the alternate pairs of chambers 17 and 18 by the flip-flop valve mechanism 22 which is of conventional design and similar to the valve means disclosed in the US. Patent No. 2,942,579 of W. A. Morrison, issued June 28, 1960.

The flip-flop valve mechanism 22 includes a front plug, also designated 22, a perforated rear plate or disc 24 spaced above the plug 22 and a washer-shaped flip-flop valve vane 25 interposed between the plug 22 and the disc 24. The valve mechanism 22 is mounted in the casing 2 between the backhead 4 and the cylinder 9. The cylinder 9 and plug 22 are keyed together to prevent relative rotation between these members.

The flip-flop valve vane 25 is arranged to rock between alternate positions wherein fluid pressure is admitted from the axial bore 5 in the backhead 4 alternately to a pair of inlets 26 and 2'7 provided in the plug 22. The flip-flop valve vane 25 is provided with a V-shaped bottom face having an apex which is located midway between the inlets 26 and 27 and rests on the top end of the plug 22 to provide the rocking fulcrum for the valve vane 25.

The inlets 26 and 27' in the plug 22 are designated an advancement inlet 26 and a retraction inlet 27, thus distingnishing them from each other by their functions or purposes. The advancement inlet 26 opens into a longitudinal advancement passage 29 formed in the drill body between the outer casing 2 and the drill cylinder 9 while the retraction inlet opens into a longitudinal retraction passage 30 likewise formed in the drill body between the outer casing 2 and the cylinder 9 and angularly displaced from the advancement passage 29.

The advancement passage 22 communicates with the advancement chambers 17 by ports 31 drilled in the cylinder 9 and the retraction passage 3i! communicates with the retraction chambers 18 by similar ports 32 drilled in the cylinder 9.

Each of the chambers 17 and 18 is exhausted through exhaust ports 34 to a longitudinal exhaust passage 35 also provided in the drill body between the outer casing 2 and the cylinder 9 and running to the front end of the drill where it empties through ports 36, shown in dotted lines in FIG. 1, to the space between the bit 3 and the front end of the cylinder S. From there, the exhaust fluid flows downwardly between the splines 37 on the bit and the bit chuck 38 fixed to the bottom of the drill body and around the end of the bit 3 where it is useful for hole cleaning purposes, as is conventional. It will be understood that the advancement passage 29, the retraction passage 30 and the exhaust passage 35 are angularly displaced from each other in the drill body.

The operation of the piston Iii and flip-flop valve 25 is believed to be well understood in the art. The valve 25 is current actuated which means that it is moved or rocked between alternate positions closing one or the other of the inlets 26 or 27 by the sudden reduction of pressure in the particular inlet which is open, resulting from the air being exhausted from the piston chambers connected to that open inlet. In other words, when the valve 25 is in a position uncovering the retraction inlet 27, it admits compressed air to the retraction chambers 18 causing the piston to move rearwardly. As the exhaust ports 34 are uncovered by the piston 10, the air pressure in the retraction chambers 18 and in the retraction passage 3% is suddenly lowered, creating a differential of pressure on the opposite faces of the valve 25 which snaps or rocks it closed over the inlet 27. At the same time, the upward or rearward movement of the piston 10 in the cylinder 9 compresses the air in the advancement chambers 17 which aids in snapping the valve 25 to its alternate position. In the new position of the valve 25, it opens the advancement inlet 26 and compressed air is admitted to the advancement chambers 17 through the passage 29, causing the piston 10 to reverse its movement and begin an advance stroke.

The longitudinal passages 29, 3d and 35 are formed in the drill body by spacing the cylinder 9 inwardly from the casing 2 and by forming ribs on the exterior of the cylinder 9 for dividing and separating the several longitudinal passages 29, 3t and 35 from each other. The invention in this application lies in the novel manner in which the longitudinal passages 29, 3t and 35 are arranged in the drill body.

The cylinder 59 is shown in its disassembled condition in FiGS. 7 and 8. Both of the longitudinal advancement and retraction passages 29 and Edi are arranged to converge or narrow in cross-section as they extend forwardly, toward the bit end of the drill. This convergent effect of the passages 29 and 35 is accomplished by providing the cylinder with a straight axially parallel rib 4d separating the two passages 29 and 3t; and a pair of zig-zag or stepped ribs 41 and 42, each of which divides one of the passages 29 and 3st from the longitudinal exhaust passage 35. The stepped rib 41 divides the advancement passage 29 from the exhaust passage 35' and the stepped rib 42 divides the retraction passage 30 from the exhaust passage 35. As a result of arranging the stepped ribs 41 and 42 to converge toward the straight rib iii in a forward direction, the exhaust passage 35, between the stepped ribs 41 and 42 expands in cross-section as it extends forward, a result which is desirable.

The foregoing shapes of the passages 2%, 3t? and 35 enables a more efficient use of the total available space around the exterior of the cylinder 9. T apering the crosssections of the passages 29, 3d and 35 allows them to be large at the points where they carry large volumes of fluid and small where they carry small volumes of fluid. In the case of both the advancement and retraction passages 29 and 3d, the volume of fluid carried in these passages is large at the rear end of the drill and becomes less in a forward direction each time some of the fluid volume is delivered to one of the piston chambers 17 and 18. In other words, the rear portions of the passages 29 and 30 must carry a suflicient volume of fluid to drive all of the piston chambers 17 and 18 and the front portions of these passages need only carry enough fluid to supply the front pair of piston chambers 17 and 18.

In a like manner, the rear end of the exhaust passage needs to be only of a suflicient size to carry the exhaust fluid from one pair of piston chambers 17 and 18 while the front portion of the exhaust passage needs to be large enough to carry the exhaust fluid from all of the piston chambers.

FIG. 9 depicts the exterior of the cylinder 9 if one were to cut the cylinder longitudinally and spread its periphery into a plane. This form of illustration is believed to clearly show the relationship between the ribs 49 and 42.

In the modification shown in FIGS. 10 to 12, the stepped ribs 41 and 42 are replaced by helical ribs 44 and 45, thus forming passages 29, 39 and 34 having a uniformly tapering cross-section, instead of a stepped cross-section. In both embodiments, the desirable result is believed to be substantially the same.

It should be understood that both of the embodiments illustrated and described have passages which are progressively reduced in cross-sectional area between opposite ends. Hence, the term progressive reduction" applies to both the stepped passages shown in FIGS. 1 to 9 and the uniformly tapering passages shown in FIGS. 10 to 12.

Although preferred embodiments of the invention have been illustrated and described in detail, it will be understood that the invention is not limited simply to these embodiments but contemplates other embodiments and variations which utilize the concepts and teachings of this invention.

Having described my invention, I claim:

1. A rock drill comprising:

(a) an elongate cylindrical body;

(b) a piston slidably mounted in said body and having several longitudinally spaced pressure actuating areas;

(0) each of said areas cooperating with said body to form a separate chamber adapted to receive fluid pressure for reciprocating said piston back and forth within said body;

(d) said chambers including a plurality of piston advancement chambers adapted to receive fluid pressure for driving said piston forward in said body and a plurality of piston retraction chambers adapted to receive fluid pressure for driving said piston rearward in said body;

(e) valve means at the rear end of said body for alternately admitting fluid pressure to said advancement and retraction chambers;

(f) and a pair of passages in said body extending forward from said valve means for respectively feeding fluid pressure to said advancement and retraction chambers, the cross-section of each of said passages being progressively reducedin area as the passage extends forward.

2. The rock drill of claim 1, including:

(a) a longitudinal exhaust passage formed in said body for exhausting fluid pressure from said chambers, said exhaust passage having a cross-sectional area which progressively increases as it extends forward.

3. The rock drill of claim 2 wherein:

(a) said passages are reduced in cross-section between their ends in several abrupt steps.

4. The rock drill of claim 2 wherein:

(a) said passages are uniformly reduced in cross-section between their ends.

5. The rock drill of claim 1 wherein:

(a) said cylindrical body includes an outer sleeve and an inner cylinder having its exterior spaced from the interior of the sleeve by integral ribs formed on said cylinder and separating said passages from each other.

6. The rock drill of claim 5 wherein:

(a) said ribs are located on said cylinder to provide said progressive reduction in cross-sectional area of said passages.

References Qied in the file of this patent UNiTED STATES PATENTS 1,031,528 Cole July 2, 1912 2,916,205 Litz ec. 8, 1959 2,946,314 Nast July 26, 1960 

1. A ROCK DRILL COMPRISING: (A) AN ELONGATE CYLINDRICAL BODY; (B) A PISTON SLIDABLY MOUNTED IN SAID BODY AND HAVING SEVERAL LONGITUDINALLY SPACED PRESSURE ACTUATING AREAS; (C) EACH OF SAID AREAS COOPERATING WITH SAID BODY TO FORM A SEPARATE CHAMBER ADAPTED TO RECEIVE FLUID PRESSURE FOR RECIPROCATING SAID PISTON BACK AND FORTH WITHIN SAID BODY; (D) SAID CHAMBERS INCLUDING A PLURALITY OF PISTON ADVANCEMENT CHAMBERS ADAPTED TO RECEIVE FLUID PRESSURE FOR DRIVING SAID PISTON FORWARD IN SAID BODY AND A PLURALITY OF PISTON RETRACTION CHAMBERS ADAPTED TO RECEIVE FLUID PRESSURE FOR DRIVING SAID PISTON REARWARD IN SAID BODY; (E) VALVE MEANS AT THE REAR END OF SAID BODY FOR ALTERNATELY ADMITTING FLUID PRESSURE TO SAID ADVANCEMENT AND RETRACTION CHAMBERS; (F) AND A PAIR OF PASSAGES IN SAID BODY EXTENDING FORWARD FROM SAID VALVE MEANS FOR RESPECTIVELY FEEDING FLUID PRESSURE TO SAID ADVANCEMENT AND RETRACTION CHAMBERS, THE CROSS-SECTION OF EACH OF SAID PASSAGES BEING PROGRESSIVELY REDUCED IN AREA AS THE PASSAGE EXTENDS FORWARD. 